Unicode key segments provide a challenge for two reasons:
Unlike all other key segments previously implemented, the number of bytes stored in the key and the number of bytes of source data used to construct the key are not the same.
The derivation of the binary sort key (segment) stored in the index from the source data is not a simple transformation.
To accommodate both of these challenges, FairCom DB incorporated an “extended key segments” feature. The concept of an extended key segment can be applied to virtually any non-standard key segment. Unicode is one such implementation of extended key segments.